Instrumente zur Chemisorption

Für Katalysatoren mit besserem Design, besserer Wirksamkeit und besserer Leistung ist ein tiefgreifendes Verständnis von Oberflächenstruktur und Oberflächenchemie des katalytischen Materials erforderlich. Chemisorption wird genutzt, um den Wirkungsgrad eines Katalysators bei der Förderung der gewünschten Reaktion zu bestimmen und um die Abschwächung der katalytischen Aktivität/Regeneration in Laufe der Zeit zu beobachten.

Chemisorption wird verwendet, um die Anzahl der oberflächenaktiven Stellen zu bestimmen, welche zur Förderung einer bestimmten Katalysereaktion genutzt werden. Für die Messung der Chemisorption gibt es folgende wichtige Parameter: Bereich des aktiven Elements, Metalldispersion, Oberflächensäuregrad, exponierter Anteil des aktiven Elements.

Während des Chemisorptionsprozesses teilen sich die adsorbierenden Gas- oder Dampfmoleküle in Atome, Radikale oder Ionen, die eine chemische Bindung mit der Adsorptionsstelle eingehen. Bei dieser Interaktion teilen sich das Gas und die feste Oberfläche Elektronen; dies kann auch als Bildung eines Oberflächenverbunds angesehen werden.

Wir bieten zwei instrumentelle Verfahren zur Chemisorptionsanalyse: das statische volumetrische Verfahren und das dynamische (Flüssiggas-) Verfahren. Ersteres wird vom Micromeritics ASAP 2020Plus angewendet, welcher in einem großen Druckbereich arbeitet. Die Instrumentenreihen 3Flex Chemi, Chemisorb und AutoChem nutzen das dynamische Chemisorptionsverfahren. Diese drei Instrumente verwenden Puls-Chemisorption in einem dynamischen Flusssystem, um die aktive Oberfläche zu titrieren.

3 Flex Chemisorption Option

Catalyst Characterization:

The 3Flex Chemisportion Instrument permits researchers to obtain valuable information about the physical or chemical properties of catalysts, catalyst supports and a variety of other materials. This model can easily switch from chemisorption to physisorption in less than 3 minutes to provide advanced analyses on the active surface area of the sample material.

Features and Benefits:

  • VCR seals provide higher levels of system cleanliness, low outgas rates, and base pressures. The result is accurate low pressure chemisorption isotherms and the ability to measure oxygen-sensitive materials.
  • Standard high-precision mass flow controller provides extremely accurate, programmable gas control.
  • High-temperature furnace (up to 1100 °C) provides quick and accurate ramp rates to desired temperature with precise temperature control and repeatability (±1 °C).
  • A total of twelve gas inlets allow multiple probe gases to be investigated maximizing efficiency and range of applications.
  • Superior temperature control maintains accuracy and repeatability in monotonic isotherms.
  • Design permits transition from chemisorption to micropore physisorption within minutes.
  • New high-temperature, precision quartz cell improves accuracy and sensitivity for challenging analyses.
  • Heated vapor can also be used as the adsorptive for chemical adsorption analyses.
  • Kalrez, Viton, or Buna 0-rings provide maximum flexibility for chemical compatibility.

3 Flex Chemisorption TCD

The 3Flex TCD is our newest addition to the expanding capabilities of the 3Flex instrument family. Dynamic chemisorption analyses are available to the user with the addition of an integral thermal conductivity detector. This new feature allows the user to perform temperature programmed reduction (TPR), oxidation (TPO), desorption (TPD), and reduction reactions (TPRx). The 3Flex TCD also has an option for pulse chemisorption analyses which can be performed with manual injections or automatically with the optional injection loop.

Features and Benefits:

  • Industry exclusive, localized loop valve temperature measurement and control improves precision, signal detectability and repeatability of the temperature-sensitive TCD detector.
  • Time, temperature, and TCD signal are recorded via the newly enhanced MicroActive software. In addition to data collection a full suite of signal processing tools are available to transform raw data to sample property information. These tools include: peak integration, peak deconvolution (curve fitting) and calculation of active surface area. crystallite size, and dispersion.
  • Full versatility; change from chemisorption experiments to physisorption analysis in minutes.

ChemiSorb 2720/2750

Catalyst Characterization:

The ChemiSorb 2720 and ChemiSorb 2750 can be equipped to perform chemical and physical adsorption tests that are central to the development, testing, and production of catalysts. They employ the dynamic (flowing gas) technique of analysis by which the quantity of gas taken up by the sample or released from the sample surface is monitored by a Thermal Conductivity Detector (TCD). Data obtained by the instruments can be used to calculate key parameters for catalyst characterization: metal dispersion, active surface area, BET surface area, average crystallite size, surface acidity or basicity, and activation energy via first order kinetic models.

The ChemiSorb 2750 - Higher Precision and Versatility:

The ChemiSorb 2750 (built upon the same design elements as the Chemisorb 2720) has been further enhanced with the addition of an injection loop for pulsing active gases on the catalyst and features an enhanced dual-port design that allows in-situ preparation and analysis of two samples. Its dual-function sample ports have the capability to be used as either an analysis port or a degas port, eliminating the need to move the sample. This requires less effort and reduces the chances of contaminating an activated sample from exposure to stray gases.

The ChemiSorb 2720 - Versatility in an Inexpensive Chemisorption System:

This basic system without the TPx option makes chemisorption and physisorption analyses affordable to even the most modestly funded laboratories. The instrument rapidly and accurately performs pulse chemisorption studies and surface area analyses. The ChemiSorb 2720 features one port dedicated to performing the sorption analysis and a second port designed for sample preparation. It also features a built-in cooling fan for the sample port, four carrier gas inlets, one prep gas inlet, and the optional capability to accommodate a mass spectrometer or other external detector attached at the exhaust port. In addition to chemisorption experiments that include determining the percent metal dispersion, active metal area, crystallite size, and quantifying acid and base sites, a range of physisorption experiments including BET surface area, Langmuir surface area, and total pore volume can also be conducted. Hands-on calibration and dosing procedures make it an excellent teaching tool for gas-solid surface interaction studies.

 

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Chemisorb HTP

High Throughput Chemi Analyzer:

Optimum design and efficient utilization of catalysts require a thorough understanding of the surface structure and surface chemistry of the catalytic material. Chemical adsorption analyses can provide much of the information needed to evaluate catalyst materials in the design and production phases, as well as after a period of use.
Optimum design and efficient utilization of catalysts require a thorough understanding of the surface structure and surface chemistry of the catalytic material. Chemical adsorption analyses can provide much of the information needed to evaluate catalyst materials in the design and production phases, as well as after a period of use.

The ChemiSorb HTP is a fully-automated high-throughput chemisorption analyzer that determines the percent metal dispersion, active metal surface area, size of active particles, and surface acidity of catalyst materials. A major advantage of this instrument is its six analysis stations. Multiple analyses can be run simultaneously or in parallel on one instrument not only saving time for busy catalyst operations, but providing economy of lab space.

The ChemiSorb HTP features a vacuum system and manifold with constantly monitored pressure transducers on each of its six analysis stations. Each port is also equipped with a furnace enabling independent control of sample temperature and ramping from 10 oC above ambient to 700 oC. The temperature is recorded with each equilibrium pressure to provide the highest quality isotherms possible. An equilibration option allows the user to specify different equilibration times. A mass flow controller is installed in each port to ensure accurate and reproducible flow through the sample. Up to twelve different gases can be attached to the ChemiSorb HTP simultaneously.

Degas/sample preparation is done in-situ prior to analysis. Samples may be added or removed from each station without disturbing the treatment of other samples undergoing preparation or analysis. The instrument features long unattended analysis times and a high-throughput mode that allows the user to start multiple parallel analyses.

The ChemiSorb HTP analysis program operates in a Windows® environment. This makes operation of the analyzer easier and allows the user to run other applications while an automatic operation is in progress. The report system provided in the analysis program allows the user to manipulate and customize reports in a variety of ways. Zoom in on portions of the graphs or shift the axes to examine fine details. Graphs and data can be copied to the clipboard and pasted into other applications. Reports can be customized with a choice of fonts and a company logo added to the report header.

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AutoChem II 2920

The AutoChem II 2920 is a fully automated chemisorption analyzer that can provide your laboratory with the ability to conduct a comprehensive array of highly precise studies of chemical adsorption and temperature- programmed reactions. With this single instrument, you can acquire valuable information about the physical properties of your catalyst, catalyst support, or other materials. It can determine catalytic properties such as percent of metal dispersion, active metal surface area, acid strength, surface acidity, distribution of strength of active sites, BET surface area, and more. The AutoChem II 2920 performs pulse chemisorption, temperature-programmed reduction (TPR), desorption (TPD), oxidation (TPO), and reaction analyses and does it automatically.

Features and Benefits:

  • Four internal temperature-controlled zones can be heated independently up to 150 °C. This prevents condensation in the flow path.
  • Low internal plumbing volume assures high resolution, fast detector response, and reduces error when calculating gas volumes.
  • Highly sensitive linear thermal conductivity detector (TCD) assures the calibration volume remains constant over the full range of peak zamplitudes so the area under the peak is directly proportional to the volume of gas reacted.
  • Four high-precision mass flow controllers provide extremely accurate, programmable gas control. This assures a stable baseline and accurate determination of gas volumes.
  • Corrosion-resistant detector filaments are compatible with most destructive gases and reduce the likelihood of filament oxidation.
  • Clamshell furnace can heat the quartz sample reactor to 1100 °C. Any number of ramp rates and sequences facilitate customized experiments. The KwikCool feature cools the furnace temperature rapidly down to near ambient, reducing analysis time and increasing throughput.
  • Four gas inlets each for the preparation, carrier, and loop gases permit four-gas sequential experiments, such as TPR/TPO cycles.
  • Mass spectrometer port and software integration allows virtually simultaneous detection on both the thermal conductivity detector and mass spectrometer.
  • Optional Vapor Generator permits analysis using vaporized liquids in an inert carrier stream.
  • Optional CryoCooler enables the start of an analysis at sub-ambient temperature.

AutoChem 2950 HP

Superior Performance Under Extended Pressure:

Micromeritics’ AutoChem 2950 HP Chemisorption Analyzer is an automated high-pressure catalyst characterization system that is capable of preparing and analyzing samples at elevated pressures up to 1000 psia and at temperatures from -100 to 1100 °C. The instrument can perform a variety of experiments including pulse chemisorption, BET surface area, temperature-programmed reduction (TPR), desorption (TPD), oxidation (TPO), and reaction analyses.

Equipped with many of the features of Micromeritics’ AutoChem II 2920, the AutoChem HP is suitable for a variety of applications including fuel cell and hydrogen storage research. This microreactor, combined with a mass spectrometer, can also be used to determine product yields and catalytic activity under commercially viable conditions. The use of a microreactor in the development process is a cost-effective alternative to pilot plants for many development projects. A microreactor is also an affordable option for small start-up companies that cannot afford to invest in a pilot plant to demonstrate their process.

Features and Benefits:

  • Allows preparation and analysis of sample at pressures up to 1000 psia with built-in safety checks.
  • Versatile analysis protocol permits complex sequencing and experimental design.
  • In situ experiments with virtually unlimited steps.
  • Records pressure as part of the experiment.
  • Capable of TPD, TPR, TPO, BET, and pulse chemisorption.
  • Three mass flow controllers and an electronically controlled pressure regulator provide precise gas control.
  • Twelve gas inlets – four each for preparation, carrier, and loop gases.
  • Stainless-steel sample tubes are capable of withstanding temperatures and pressures well above the system’s limits.
  • An interactive reporting system that includes an extremely versatile graphic user interface allowing custom presentation of results.

ASAP 2020 Plus Chemisorption Option

Accelerated Surface Area and Porosimetry System:

Sophisted Design, Intuituve Operation, Research-Grade Results.

The Micromeritics ASAP 2020 Plus integrates a variety of automated gas sorption techniques into a single, but powerful, table-top instrument. The system is designed to provide high-quality surface area, porosity, chemisorption and physisorption isotherm data to materials analysis laboratories with ever-expanding analytical requirements. The ASAP 2020 Plus provides maximum versatility over a remarkable range of applications to meet your specific needs.

With more installed instruments in more countries for more users, the ASAP family of products have proven to be the instruments of choice worldwide when researchers require precise, high-quality gas adsorption data.

Advanced Capabilities through Optional Configurations:

The ASAP 2020 Plus can be configured to your specific needs with the option of upgrading at a later date as your analytical requirements change, maximizing the utility of this instrument and your investment.

Choose from low surface area, to heated vapor, to micropore capability. Add a cryostat, an external detector, or configure the unit for enhanced chemical resistance when working with aggressive vapors. The ASAP 2020 Plus permits one instrument to accommodate almost any surface characterization need in your lab.

Unique and Innovative Isothermal Jacket Cold Zone Control:

Isothermal jackets are guaranteed for the life of the instrument and ensure a constant thermal profile along the full length of both the sample and saturation pressure (P°) tubes.

Design Versatility

  • Two independent vacuum systems permit simultaneous preparation of two samples while analyzing another. This maximizes your personnel productivity and your return on time invested.
  • Continuous saturation pressure (P°) monitoring and unique Isothermal Jacket Cold Zone Control provide a stable thermal environment for both saturation pressure and adsorption. Spend time on results instead of controlling temperature variations.
  • The ASAP 2020 Plus is configurable with many optional accessories to meet your specific analytical requirements.